1. Field of the Invention
This invention relates generally to wheel trim and more particularly to a system for providing clearance between a wheel cover and a wheel rim.
2. Antecedents of the Invention
Enhanced wheel appearance, not only in automobile wheels but, in addition, wheels of sport utility vehicles and trucks has been a continuing objective in both original equipment manufacturing and aftermarket industries.
While steel wheels have been the cost and weight efficient approach at providing requisite strength and utility, the appearance of stock steel wheels left much to be desired from an aesthetic standpoint. In automotive applications, manufacturers constantly strove to meet fuel efficiency goals while at the same time, sought to provide attractive appearance at low cost. Automotive manufacturers attempts at achieving such objectives resulted in steel wheels to which light weight plastic wheel covers were mounted. The plastic wheel covers were generally injected molded and a variety of surface coatings were applied to the outer face of the wheel cover.
As optional equipment in economy vehicles and standard equipment in luxury vehicles, original equipment manufacturers offered cast alloy wheels which did not require wheel covers. The costs of cast alloy wheels, however, was significant; such wheels were generally not selected as an option by cost conscious consumers. Aftermarket manufacturers offered replacement wheel covers, chromed or plated steel wheels as well as cast alloy wheels.
Various systems have been devised for mounting wheel covers to vehicle wheels. Mounting or retention systems employed retentive forces between the wheel cover and the wheel which were applied either in radial or axial directions.
In some radial retention systems, as exemplified by U.S. Pat. No. 4,232,907, sharp teeth or barbs on a plurality of metal spring leaves engaged a wheel rim. The spring leaves were individually mounted to the wheel cover or comprised part of a metal grip ring which was received within an annular channel on the inner face of a wheel cover, as illustrated in U.S. Pat. No. 3,876,257, owned by the assignee of the present invention.
Radial retention systems suffered from certain disadvantages, among which were that the sharp barbs were prone to scratch protective paint coatings from the surface of the wheel rim, exposing the rim to moisture and road salts, which accelerated corrosion. Also, stresses were generated within the body of the wheel cover by the engagement between the springs and the wheel rim. With respect to plastic wheel covers, such stresses often resulted in cracks or other failures. Further, due to the elevated temperatures generated by the vehicle braking system components, tire flex, etc. plastic wheel covers often attained elevated temperatures which degraded structural rigidity, resulting in distortion of the wheel covers, reduction in retentive forces and consequent loss of wheel covers.
Attempts to avoid scratching of paint in radial retention systems resulted in the employment on non-scratch leaf springs, as illustrated by U.S. Pat. No. 5,542,751, assigned to the assignee of the present invention and the utilization of spring wire rings carried in struts and employed to outwardly bias engagement elements to seat in a concave draw bead step of the wheel rim, as exemplified by U.S. Pat. No. 4,740,038.
Axial wheel cover retention systems have employed threaded caps to engage wheel mounting lugs projecting beyond the ends of lug nuts, as illustrated in U.S. Pat. No. 4,895,415 and U.S. Pat. No. 5,222,785. The caps were tightened against the end of the lug nut, compressing the wheel cover between the lug nut and the cap.
Many retention systems positioned the periphery of the wheel cover in abutment with the peripheral edge of the wheel rim. Such abutting contact often resulted in axial outward flexing of the periphery of the wheel cover. The engagement between the wheel cover and the periphery of the wheel rim also resulted in rubbing contact and the generation of squeaking noises when the wheel rim moved relative to the wheel cover, e.g., when the wheel rim flexed.
While a need for spacing wheel covers from the periphery of the wheel rim was previously perceived, it was for a different objective, i.e. to provide an adequate clearance for the insertion of a screwdriver to pry the wheel cover loose, as disclosed in U.S. Pat. No. 4,427,238. In U.S. Pat. No. 4,427,238, a plurality of flanges having shoulders which engaged a wheel weight channel portion of the wheel rim provided the screwdriver clearance.
A tire was mounted to a wheel rim with its annular tire bead circumscribing a tire bead seat zone comprising portions of the rim between the peripheral edge of the wheel rim and a draw bead step. The tire bead seat zone was subject to flex during road engagement whereas the wheel cover was not subject to such flex. Abutting engagement between the locating stops and the wheel weight channel did not prevent the generation of squeaking noises upon relative movement between the two surfaces in engagement. U.S. Pat. No. 4,427,238 did not address the problem perceived by the inventor herein.
One of the drawbacks associated with the utilization of flanges in engagement with the wheel weight channel of a wheel rim was that the position of the wheel cover, hence the position of the flanges, was fixed relative to the wheel by a valve stem cut out in the wheel cover. The position of wheel weights carried within the wheel weight channel was variable, however, being dependent upon the requisites for balancing the entire wheel and tire assembly. Often, the flanges would not be able to seat against the channel because of interference with the wheel weights.
It has also been known to employ flanges on the inner face of a wheel cover for the purpose of centering the wheel cover to be coaxial with the wheel, as illustrated in U.S. Pat. Nos. 4,884,851, 4,146,273 and 3,867,257. Since such arrangements provided abutting contact between the flange portions of the wheel cover and a convex inner shoulder of the wheel weight channel and the inner shoulder of the wheel weight channel was subject to flex; squeaking noises were not alleviated.
In addition, the flexing of portions of the inner shoulder resulted in the wheel cover being moved axially outwardly from the wheel, further increasing the stresses applied to the wheel cover, potentially loosening the wheel cover retention and increasing the likelihood for the wheel cover to be thrown off during operation of the vehicle.